Roku Community Streaming Expert I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well. If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X
When removing a channel, please make sure to restart your Roku device before adding the channel back again, specifically in that order.
If you are still experiencing an issue with the NBC channel, have you already tried contacting the channel provider to see what insight they can provide? Many channels on Roku are developed and maintained by the channel provider themselves.